With the recent tendency toward westernized eating habits in Japan, intake of high fat diet continues to increase. According to a National Nutrition Survey in Japan (1999), it is reported that although their energy intake is decreasing every year, their fat energy ratio exceeds the reasonable proportion of 25%, and 50 to 60% of people over 60 are recognized to have high triglyceride and cholesterol values [A Summary of 1999 National Nutrition Survey in Japan by The Ministry of Health, Labor and Welfare, Rinsho Eiyo (Clinical nutrition) 2001; 98(5): 577-588].
Obesity is one of the most severe diseases in present day society, caused by excessive fat intake. The excessive fat intake causes not only obesity, but also disorders caused by obesity such as diabetes, hyperlipidemia, hypertension and arteriosclerosis. In Japan, Mazindole® as an anorectic drug is only one therapeutic drug with official approval for treating obesity. However, this drug is reported to have side effects such as excessive thirst (mouth dryness), constipation, epigastric distress, nausea and vomiting [Rinsyo Hyouka (Clinical evaluation), 1985; 13(2): 419-459, Clinical evaluation, 1985; 13(2): 461-515]. In overseas, Xenical® as a lipase inhibitor which suppresses fat absorption in the gastrointestinal tract, is on market as an obesity treatment drug. However, this drug is also reported to have side effects such as fatty stool, increased stool frequency, soft stool, diarrhea and stomachache. Therefore, using this drug is sometimes accompanied by concerns about safety (The Lancet 1998; 352:67-172).
To prevent obesity, it is advantageous to reduce the caloric intake by controlling diet. However, it requires careful guidance on nutrition making it difficult to practice in daily life. Therefore, inhibiting the absorption of dietary lipids in the body in a safe and healthy manner is practical and useful for treatment of obesity and related diseases and in promoting health.
With these facts in mind, the development of a “food for specified health uses” which is safe to use and is proven to be effective in treating humans is attracting a lot of attention. Food materials which inhibit increase of serum triglyceride after a meal, such as: a globin protein decomposition product that suppresses fat absorption by pancreatic lipase inhibitory activity [J. Nutr. 1988; 128: 56-60, Nihon Eiyou Shokuryou Gakkai-shi (Journal of Japanese society of Nutrition and Food Science) 1999; 52(2): 71-77, Kenkou Eiyou Shokuhin Kenkyu (Health food and nutrition food Research) 2002; 5(3): 131-144]; diacylglycerol with different digestion and absorption features compared to triacylglycerol (J. Am. Coll. Nutr. 2000; 19(6): 789-796, Clin. Chim. Acta. 2001; 11(2): 109-117); eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA) purified from fish oil; are on market as foods for specified health use until now.
On the other hand, reports on lipid-improving effect of oolong tea are: significant decrease in blood triglyceride after drinking 1330 ml/day of commercial oolong tea for 6 weeks [Nihon Eiyou Shokuryou Gakkai-shi (Journal of Japanese society of Nutrition and food science) 1991; 44(4): 251-259]; and oral administration of oolong tea (2 g×4/day) for 6 consecutive weeks to 102 males and females with simple obesity resulted in more than 1 kg weight loss in 67% of the subjects and significant improvement in the subjects with high blood acylglycerol after taking oolong tea [Nihon Rinsho Eiyou Gakkai-shi (The Japanese Society of Clinical Nutrition Magazine) 1998; 20(1): 83-90]. These reports show that although drinking a large quantity of oolong tea is recognized to be effective, it is difficult in daily life to continue drinking such large quantities of a drink such as oolong tea. Further, simply providing concentrated oolong tea is not an appropriate and a practical option, due to its strong bitterness and astringency and increased caffeine content.
Speaking of high-molecular weight polyphenols (polymerized catechins) contained in oolong tea and other tea products, they exhibit various beneficial effects whereas they are less astringent and bitter than other tannins and non-polymerized catechins. It is therefore desired to establish an efficient method by which the catechins contained in oolong tea and other tea products can be separated into non-polymerized catechins and polymerized catechins.
It has been known that a variety of ingredients in tea can be separated by various resins. For instance, it has been known that detanning and decaffeination are possible by treating with activated charcoal. However, there has not been known any effective method that can selectively separate polymerized catechins from non-polymerized catechins by means of an adsorbent such as activated charcoal or an adsorbing resin.    Non-patent document 1: A Summary of 1999 National Nutrition Survey in Japan by the Ministry of Health, Labor and Welfare, 2001 98(5): 577-588    Non-patent document 2: Rinsho Hyouka (Clinical nutrition) 1985; 13(2): 419-459    Non-patent document 3: Rinsho Hyouka (Clinical nutrition) 1985; 13(2): 461-515    Non-patent document 4: The Lancet 1998; 352: 67-172    Non-patent document 5: J. Nutr. 1988; 128: 56-60, 1988    Non-patent document 6: Nihon Eiyou Shokuryou Gakkai-shi (Journal of Japanese Society of Nutrition and Food Science) 1999; 52(2): 71-77    Non-patent document 7: Kenkou Eiyou Shokuhin Kenkyu (Health food and nutrition food Research) 2002; 5(3): 131-144    Non-patent document 8: J. Am. Coll. Nutr. 2000; 19(6): 789-796    Non-patent document 9: Clin. Chim. Acta. 2001; 11(2): 109-117    Non-patent document 10: Nihon Eiyou Shokuryou Gakkai-shi (Journal of Japanese Society of Nutrition and food science) 1991; 44(4): 251-259    Non-patent document 11: Nihon Rinsho Eiyou Gakkai-shi (The Japanese Society of Clinical Nutrition Magazine) 1998; 20(1): 83-90